Calibrating means for a humidity control device



Dec. 25, 1962 14. C ZINE C. E. OHLHEISER CALIBRATING MEANS FOR AHUMIDITY CONTROL DEVICE Original Filed June 20, 1955 DenuMm/FyuvsAPP/9R4 Tu:

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' JNVENTOR. (Aura/v 5. 0/11/1515 /A/M H m United tates Patent Originalapplication June 20, 1955, Ser. No. 516,462, now Patent No. 2,943,245,dated June 28, 1960. Divided and this application June 13, 1960, Ser.No. 35,796

Claims. (Cl. 116-133) This is a division of applicants co-pendingapplication, Serial No. 516,462, filed June 20, 1955, now US. Patent No.2,943,245, entitled Humidity Control Device.

This invention relates to humidity control devices, and moreparticularly to means to apply a temperature correction to an electricalhumidity control apparatus.

A main object of the invention is to provide a novel and improved meansfor applying a temperature correction to an electrical humidity controlapparatus when the apparatus is calibrated for operation around aspecified value of relative humidity.

A further object of the invention is to provide an improved calibratingmeans for a humidity-responsive electrical control device, said meansbeing simple in construction, being easy to apply to the control device,and enabling a suitable temperature correction to be applied to thedevice when it is set for operation around a specified value of relativehumidity.

A still further object of the invention is to provide an improvedcalibrating means for a humidity-responsive control device which enablesa required temperature correction to be applied to the device withoutinvolving recourse to temperature correction charts or tables and whichenables the device to be accurately set to respond to a specifiedcondition of relative humidity.

Further objects and advantages of the invention will become apparentfrom the following description and claims, and from the accompanyingdrawings, whereinz' FIGURE 1 is a schematic wiring diagram of ahumidity-responsive control device of a type with which the calibratingdevice of the present invention is adapted to be employed, the diagrambeing shown schematically with a'plug-in-calibrating resistor unit forsetting the apparatus for operation? around a specified value ofhumidity.

FIGURE 2 isa fragmentary front elevational view of a humidity controlapparatus having means according to the present invention for applying atemperature correction when the apparatus is calibrated for operationaround a specified value of humidity.

FIGURE 3' is' a fragmentary cross-sectional view taken substantiallyon-the line 3-3 of FIGURE 2.

Referring to the drawings, 11 generally designates the schematicwiring'diag'ram of ahumidity-sensitive control device, described indetail in applicants US. Patent No. 2,943,245. The device includes ahousing 12 having parallel' side walls 13 and 14 and a front cover 18,as shown in FIGURE 3, provided'with an aperture 19 aligned withthe-shaft 46 of a' rheostat 45 mounted on the chassis 21, said chassisservingas the support for the electrical cornponentsof the device, as-isfully described and illustrated inthe above mentioned Patent No.2,943,245.

As shown in FIGUREI, thehumidity-sensitive control device 11 comprises-avacuum tube 22 having a plate-23, a screen grid 24, a controlgrid 25, acathode 26, and a filament 27. The device is mounted in the housing 12on the chas'sis21'.

The device includes terminals'31, 32, 33' and 34. Terminals 33 and 34are connected in series with the power supply ofa' dehumidifyingapparatus 35, for dehumidifying the area to be controlled.

The chassis 21 is provided with a suitable socket 36 3,070,062 PatentedDec. 25, 1962 receiving a conventional humidity sensing element 37 ofthe bifilar-wound type. The chassis is provided with a jack 38 having aring element 39, a stationary contact 40, and a flexible contact 41normally engaging stationary contact 40 but being moved out ofengagement therewith responsive to the insertion of a conventionalball-end plug 42 into the jack, whereby the ball 43 of the plug engagescontact 41 and the sleeve 44 of the plug engages the ring element 39.

Mounted on the chassis 21 is the rheostat 45 having the outwardlyprojecting slotted control shaft 46.

As shown in FIGURE 1, terminal 31 is connected by a wire 56 to oneterminal 57 of resistor 29. Terminal 57 is connected by a wire 58 toscreen grid 24. The other terminal 59 of resistor 29 is connected by awire 60 to cathode 26 and a terminal of filament 27. The other terminalof said filament is connected by a wire 61 to line terminal 32.

Plate 23 is connected by a wire 62 to one terminal of the winding of arelay R-2 mounted beneath chassis 21. The other terminal of this windingis connected by a wire 63 to one terminal of the winding of a secondrelay R-l mounted beneath chassis 21. The remaining terminal of thewinding of relay R-l is connected by a wire 64 to the line terminal 31-.

A first filter condenser 65 is connected across the ter-' minals of thewinding of relay R-2 and a second filter condenser 66 is connectedacross the terminals of the winding of relay R-1.

Relay R-1 has the armature 67 which is connected by a wire 68' toterminal 33. Said relay has a stationary contact 69 engageable byarmature 67 when less than a first predetermined value of plate currentflows through the winding of relay R-1. Contact 69 is connected by awire 70 to terminal 34.

Relay R-2 has the armature 71 which is connected by a wire 72 to aterminal 73 onchassis 21. Relay R-'-2 has the stationary contact 75engageable by armature 71 when less than a second predetermined value ofplate current flows through thewinding of relay R-2, said second valuebeing less than the above-mentioned first value of plate current.Contact, 75 is connected by a wire 76 to a terminal 77.

Control grid 25 is connected by a wire 78 to the sliding tap 79 of therheostat 45. The remaining terminal 80 of the rheostat is connectedthrough, a resistor 81 to the terminal 59.

Flexible jack contact 41 is connected by a wire 82 to sliding tap 79.Stationary jack contact 40' is connected by a wire 83 to one terminal-84of the. humidity sensing element socket 36. The other terminal 85 ofsaid socket is connectedth'rough a condenser 86- and a resistor 87 tothe wire'61.

It willbe apparentfrom FIGURE- I that the filament 27 is energizedthrough a circuit comprising line terminal 31,-wire 56, resistor 29,wire 60; filament 27. wire 61 and line terminal 32.- Rectified platecurrent flows between cathode 26 and plate 23, and throughtheseries-connected windings of relays R-2- and R-1 through acircuitcornprising wire 60,.ca'thode 26; plate 23, wire 62. the windingof relay R-2, wire 63, the winding of relay R1. wire6=4'v and terminal31. The amount of such current is, governed by the amplitude of thealternating current signal'on grid 25 with respect to cathode'26; Theamplitude of said signal is in-turn governed by the; resistance ofhumidity sensing element 37, since said sensingelement; is connected inseries with resistor 87:, condenser 86, rheostat 45-and resistor 81-,defining a currentpath-across'thefilament 27. Since grid 25 isconnectedto tap 79, after said tap has been adjusted to a predetermined positionthe alternating current potential ongrid 25' will vary in accordancewith changes in resistance of the humidity sensing element 37. Withincreased humidity the resistance of said humidity sensing elementdecreases, increasing the effective value of the negative signalpotential on grid 25, thus reducing the flow of rectified plate currentthrough tube 22. A reverse action occurs when the humidity decreases.

For purposes of calibration, a plug 42 is employed containing acalibrating resistance 95 having a value corresponding to the value ofthe humidity sensing element resistance at the humidity control point,namely, at the value of humidity at which the dehumidifying apparatus 35must be energized. When the plug 42 is inserted in jack 38, thecalibrating resistor 95 is substituted for the humidity sensing element37. The sliding tap 79 of rheostat 45 is then manually adjusted untilcontacts 67, 69 of relay R-l just close, the adjustment being made in adirection decreasing the resistance of rheostat 45 since this reducesthe amplitude of the signal on grid 25. When the humidity increases to avalue corresponding to the desired upper humidity limit, the relay R-1closes its contacts, energizing the dehumidifying apparatus 35. When thehumidity increases beyond this value by a predetermined amount, relayR-Z closes its contacts and energizes an alarm device 100, connectedthrough a battery 101, or other suitable power supply, to the terminals73, 77.

In order to calibrate the device, the plug 42. is inserted in jack 38and the rheostat shaft 46 is rotated. The calibrating resistor 95enables the device to be set for operation at a predetermined value ofabsolute humidity. To set the device in terms of relative humidity,temperature corrections must be applied, and one way of doing this is toprovide respective calibration plugs for respective differenttemperature bands, each calibration plug being provided with acalibrating resistor whose value includes the temperature correction. Asan alternative, and to provide a more accurate setting of the device foroperation at a desired value of relative humidity, the temperaturecorrection may be applied at the time the device is calibrated foroperation, as by means illustrated in FIGURES 2 and 3.

A plate member 20' is provided, said plate member having depending endflanges 21, 21 spaced so that the plate member 20 may be engagedtransversely over front cover 18' in the manner shown in FIGURE 3, withthe end flanges 21, 21' disposed outwardly adjacent and engaging theside flanges of the cover 18.

Rigidly secured to plate member 20 at diametrically opposite sidesthereof with respect to a central aperture 22' therein are upstandingstuds 23, 23'. Designated at i 24' is a circular scale plate havingarcuate slots 25', 25 at diametrically opposite peripheral portionsthereof, said slots being concentric with the plate 24' and beinglocated at equal radial distances thereon. The circular plate 24 isdisposed on plate member'20' with the studs 23 extending through thearcuate slots 25', as shown in FIGURE 2. Knurled nuts 26' are providedon the studs 23 to lock plate 24 in adjusted position on plate member20'.

A vertical shaft 27 extends rotatably through the center of plate 24'and through the central aperture 22 of plate member 20'. Rigidly securedto the top end of shaft 27' is a knob 28' having a pointer 29' which maybe moved along an arcuate relative humidity scale 30' inscribed on plate24'. Secured to the lower portion of shaft 27' and being rotatablyengageable through the aperture 19 is a sleeve 31'. Sleeve 31" isengageable over the top end of shaft 46, as viewed in FIGURE 3, and isprovided with a transverse pin element 32' which is engageable in theslot 70' in the top portion of shaft 46, whereby shaft 46 may be rotatedby rotating the knob 28.

The peripheral portion of circular plate 24 is inscribed with an arcuatetemperature scale 33 and the plate member 20 is inscribed with an indexpointer 34 adjacent scale 33', so that plate member 24' may be rotateduntil pointer 34' is located at the ambient temperature value on 4 scale33'. This introduces the required temperature correction. Knob 28 maythen be rotated to set pointer 29 adjacent the value of relativehumidity to be maintained in the area controlled by the device.

Plate member 20 may then be removed from the front cover 18', leavingthe device set to maintain the desired relative humidity.

While a specific embodiment of an improved calibrating means for ahumidity-responsive electrical control device has been disclosed in theforegoing description, it will be understood that various modificationswithin the spirit of the invention may occur to those skilled in theart. Therefore it is intended that no limitations be placed on theinvention except as defined by the scope of the appended claims.

What is claimed is:

t 1. Calibrating means for a humidity control device of the typecomprising a support including a calibrating impedance having arotatable shaft, said calibrating means comprising a removable mainplate member having flanges spaced to receive the support therebetweenand to thereby interlock with said support with the main plate memberdisposed over said shaft, a scale plate rotatably mounted on said mainplate member, a coupling member extending rotatably through said scaleplate and main plate member, and means on said coupling member formedand arranged to interlock with said rotatable shaft.

2. Calibrating means for a humidity control device of the typecomprising a support including a calibrating impedance having arotatable shaft, said calibrating means comprising a removable mainplate member having flanges spaced to receive the support therebetweenand to thereby interlock with said support with the main plate memberdisposed over said shaft, a scale plate rotatably mounted on said mainplate member, a coupling member extending rotatably through said scaleplate and main plate member, means on said coupling member arranged tointerlock with said rotatable shaft, a temperature scale on one arcuateportion of said scale plate, and a relative humidity scale on anotherarcuate portion of said scale plate.

3. Calibrating means for a humidity control device of the typecomprising a support including a calibrating impedance having arotatable shaft, said calibrating means comprising a removable mainplate member having flanges spaced to receive the support therebetweenand to thereby interlock with said support with the main plate memberdisposed over said shaft, a scale plate rotatably mounted on said mainplate member, a coupling member extending rotatably through said scaleplate and main plate member, a coupling sleeve secured to said couplingmember and being of suflicient length to receive said shaft, and meansin said sleeve lockingly engageable with said shaft.

4. Calibrating means for a humidity control device of the typecomprising a support including a calibrating impedance having arotatable shaft, said calibrating means comprising a removable mainplate member having flanges spaced to receive the support therebetweenand to thereby interlock with said support with the main plate memberdisposed over said shaft, a scale plate rotatably mounted on said mainplate member, a coupling member extending rotatably through said scaleplate and main plate member, a coupling sleeve secured to said couplingmember and being of suflicient length to receive said shaft, means insaid sleeve lockingly engageable with said shaft, a temperature scale onone arcuate portion of said scale plate, and a relative humidity scaleon another arcuate portion of said scale plate.

5. Calibrating means for a humidity control device of the typecomprising a support including a calibrating impedance having arotatable shaft, said calibrating means comprising a removable mainplate member having flanges spaced to receive the support therebetweenand to thereby interlock with said support with the main plate memberdisposed over said shaft, a scale plate on said main plate member formedwith a pair of opposing concentric arcuate portion of said scale plate,and a relative humidity scale slots, a pair of upstanding studs on saidmain plate memon another arcuate portion of said scale plate.

ber slidably received in said slots, wherecy to guide the scale platefor rotation on said main plate member, a ReferemeS Cited in the filfiOf this Patent coupling member extending rotatably through said scale 5UNITED STATES PATENTS plate and main plate member, a coupling sleevesecured to said coupling member and being of suificient length to2,237,653 ghafinon P 8, receive said shaft, means in said sleevelockingly engage- 214111041 kahn 194 able With Said shaft, a temperaturescale on one arcuate 215O9485 Dalzen y 1950 2,856,583 Allison Oct. 4,1958

